Control of the gray field slug during annual ryegrass establishment

Authors: GAVIN, WILLIAM - Oregon State University; HOFFMAN, G - Oregon State University; Banowetz, Gary

Submitted to: Seed Production Research at Oregon State University
Publication Type: Experiment Station
Publication Acceptance Date: 2/28/2009
Publication Date: 3/31/2009
Citation: Gavin, W.E., Hoffman, G.F., Banowetz, G.M. Control of the gray field slug during annual ryegrass establishment. Seed Production Research at Oregon State University. 2009. p. 71-76.

Interpretive Summary: Studies were conducted at three different field sites in 2007 and 2008 to compare the effectivness of seven chemical measures for controlling slug populations in new stands of annual ryegrass seed production fields. We found that weather conditions, especially the timing of fall rains, heavily influenced the utility of any of the chemicals to control slug populations. A granular formulation, Durham, was effective in reducing slug populations unless a heavy rain followed the bait application. When fall rains were delayed, and the timing of seedling emergence and slug emergence coincided, slug control was very difficult. With more normal autumn rainfall, seedling emergence preceded slug emergence and all of the formulations had an effect on slug populations.

Technical Abstract: Weather conditions, in particular soil moisture and soil and air temperature, interact with both crop seedling and slug emergence during the early autumn season. Late, or inadequate autumn rainfall in western Oregon occasionally causes the timing of emergence of newly established annual ryegrass seed crops to coincide with the emergence and increased feeding activity of slugs that damage newly emerged grass seedlings. The period of new seedling emergence is most sensitive to slug depradation, and control measures are needed to reduce crop losses. We conducted trials at three distinct field sites to determine how product type and admixtures of products could reduce slug populations during establishment of annual ryegrass Lolium multiflorum L. in the autumn of 2007 and 2008. Our goal was to identify an approach to establish grasses in low-to-high slug populated fields at the lowest possible cost to growers. Durham granular significantly reduced slugs at three sites in 2007 and 2008 unless the application was followed by heavy rain. We found that SlugFest AWF should be applied to as much green standing material as possible. The effectiveness of any formulation, or admixture was heavily dependent upon rain conditions. When autumn rains were late, as in 2008, slug control was largely ineffective because the timing of seedling and slug emergence coincided.